Projectile ignition device



Jan. 5, 1960 PROJECTILE IGNITION DEVICE Filed May 5, 1955 CARLOS J. CARDONA AND NORMAN H. MILDE v INVENTORS c. J. CARDONA ET AI. 12,919,627 7 PROJECTILE IGNITION DEVICE Carlos J. Cardona, North Hollywood, and Norman H. Milde, Palos Verdes Estates, Calif., asslgnors to McCulloch Motors Corporation, Los Angeles, Calif a corporation of Wisconsin Application May 5, 1953, Serial No. 353,032

I 1 Claim. (Cl. 89-1) The invention relates to means for firing explosives and relates in particular to a means for igniting or setting off apowder charge after it has been ejected from a launching device or gun.

It is an object of the invention to provide a simple system and means for firing a charge in a projectile at a desired time after it has been ejected from a propelling or' launching device, wherein a time-delay fuse is ignited by electrically actuated means utilizing electric current induced in a coil carried by the projectile.

A further object of the invention is to provide a simple yet dependable ignition means for igniting and dispersing a quantity of flare powder. However, the term powder is herein employed in its broad sense to mean explosives in general regardless of whether they are the slow buming or detonating types, or whether they are prepared in small granules or larger bodies.

These and other objects and advantages of the invention may be brought out in the following part of the specification wherein forms of the invention have been explained in detail for the purpose of completeness of disclosure, and not for limiting the scope of the invention which is defined in the appended claim.

Referring to the drawings which are for illustrative purposes only:

Fig. 1 is a partly schematic and partly cut-away view of a projectile launching device incorporating electromagnetic field inducing means at the launching end thereof;

Fig. 2 is a cross-sectional view of a projectile incorporating the present invention therein; and

Fig. 3 is a partly cut away view of a projectile launching device incorporating magnetic field inducing means at the launching end thereof.

Referring now to Fig. 1, there is schematically illustrated therein a propelling or launching device which includes a launching mechanism 11 such as a pneumatic or compressed air type of launcher, and a barrel or guide tube 12 projecting rightwardly from the launching mechanism. Mounted on the rightward end 13 of the barrel 12 is a retaining member 14 which is adapted to posi tion an annular induction coil 15 or other means for establishing magnetic flux in close proximity to the end of the barrel. As illustrated in Fig. l, the coil is positioned co-axially with the barrel 12 so that its major axis extends in the launching direction. Also, the leftward extremity or face 16 of the coil is positioned closely adjacent the plane 17 formed by the end face of the barrel 12. A switch 18 and a source of potential such as battery 19 are connected in series with the coil so that when switch 18 is closed, electric current will flow through the coil windings causing an electromagnetic field to build up around the coil. The flux density of the electromagnetic field will be greatest within the aperture or space 20 surrounded by the coil body 15 and adjacent the end face 17 of the barrel 12. One reason for positioning the coil 15 rightwardly of the end face 17 of the barrel is to minimize interference with the estab- Patented Jan. 5, 1960 lishment of the magnetic field within aperture 20, which is caused by the metallic barrel 12. An annular flux concentrating member 21 is positioned around coil 15 in order to increase the electromagnetic field strength or flux density within aperture 20. Member 21 may comprise any ferromagnetic material, such as iron.

The projectile 25 illustrated in Fig. 2 is adapted to be launched by being propelled through the barrel 12 and through the aperture 20 surrounded by the coil 15. Projectiles to which the present invention may be adapted may be of various types; however, the particular projectile illustrated is adapted to be exploded after a known time interval after launching to form an intensely luminous body or flare. Projectile 25 includes a metal case 26 filled with a flash mixture such as magnesium powder, which becomes brilliantly luminous on ignition and combustion. The ignition charge 28 is packed within a container 29 having a neck portion 30 which surrounds the open end 31 of a fuse guard tube 32. The opposite end of the tube is fastened to a container 33 within which an electrically ignitable element or squib 34 is positioned. A typical element of this type contains a combustible consisting of a few grains of black powder, and is adapted to ignite when an electric current is passed through it.

A time delay fuse 35 is connected between the squib 34 and the detonating charge 28 and it extends through the tube 32. The fuse illustrated comprises a fuse rope type of powder train. The container 33 is positioned within solid cylindrical member to which the projectile case 26 is fastened, the member 40 projecting leftwardly or rearwardly from the end of the case 41. Member 40 consists of a solid insulator such as a plastic material, for example, a phenolic resin. A second coil 42 is molded or embedded in the portion 43 of member 40 which projects rearwardly from the end 41 of the projectile case. Coil 42 is electrically connected in series with squib 34 by means of leads 45 and 46 which are pressed into terminals 47 and 48 to which the ends of a wire 49 are soldered. Wire 49 passes through the body of the electrically ignitable element 34.

Coil 42 is positioned in the rearward portion of the projectile with its major axis extending in the launching diretcion, which is the direction of the longitudinal axis of the guide tube 12. Coil 42 is essentially an induction element in which a voltage is generated by the passage of the coil through a magnetic or electromagnetic field. The coil turns are positioned with respect to the launching direction so that a maximum voltage is induced in the coil when the projectile is launched. The electrical current induced in the coil 42 passes through the squib wire 49 and ignites the black powder, which in turn ignites the time delay fuse rope 35. The fuserope burns toward the ignition charge which will ignite after the known time delay interval. The ignition charge will in turn ignite the flash material 27 and fragment the case 26.

The magnetic field at the end of the barrel may alternatively be established by magnetic means such as horseshoe magnet 60 illustrated in Fig. 3. Magnet 60 has pole faces 61 and 62 disposed longitudinally in the general direction of the axis of the barrel 63. A non magnetic retainer 64 is mounted at the end of the barrel to position pole faces 61 and 62 near the end 65 of the barrel 63 and adjacent an imaginary extension 66 of the cylindrical bore 67 of the barrel. So-called lines of magnetic flux extend between the pole faces and necessarily pass through a portion of the imaginary cylinder 66. When a projectile such as flare projectile 25 is launched from barrel 63, it will pass through the imaginary cylinder 66 and the induction coil 42 carried by the projectile 25 will cut through the portion of the flux 3 passing through imaginary cylinder 66. An igniting voltage will thus be induced in coil 42.

We claim:

In apparatus of the character described, a combination of a launching mechanism including a barrel having a discharge end; an annular induction coil mounted on said :barrel coaxially therewith and at the discharge end thereof; and a projectile arranged to be discharged from said barrel and comprising a case open at the rear end and having a powder charge therein; a time-delay fuse extending longitudinally in said case having at one end thereof an ignition charge arranged to effect ignition of said powder charge; a longitudinal guard tube arranged to cover said fuse; a body of insulating material closing the open end of said case and projecting outwardly therefrom, said body having an inwardly faced cavity communicating with said guard tube; an electrically sensitive ignition element disposed in said cavity and at the other end of said time-delay fuse, said ignition element comprising a combustible, which upon becoming ignited, will ignite the contiguous end of said fuse, and a Wire for conducting an electric current in proximity to said combustible; and an induction coil supported by the outwardly projecting portion of said body of insulating material and at the rear thereof so that when the projectile passes through said magnetic flux field, a current will be 4 induced in said coil to initiate a'sequence consisting of the ignition of said combustible, the burning of said time-delay fuse, the ignition thereby of said ignition charge and finally the ignition of said powder charge at a time after said projectile has been discharged from said propelling means.

References Cited in the file of this patent UNITED STATES PATENTS 29,573 1,280,579 Stone et al. Oct. 1', 1918 1 ,704,302 Ruhlemann .Q Mar. 5,-1929 1,739,921 Schuler et a1. Dec. 17, 1929 1,776,796 Ruhlemann Sept. 30, 1930 2,459,854 Swift Ian. 25, 1949 2,465,351 Busi'gnies et al. Mar. 29, 1949 2,514,359 Allison July 11, 1950 2,520,949 Meister SeptzS, 1950 2,555,384 Watt June 5, 1951: 2,557,949 Deloraine June 26, .1951 2,581,096 Gould Ian. 1, 1952 2,640,417 Bjork et al. June 2, .1953

FOREIGN PATENTS 578,153 Great Britain June 18,1946

Cranston et al. Aug. 14, 1860 

